1. Field of the Invention
The present invention is directed to a service control point in an intelligent network of the type including multiple computing units which process multiple identification number or "IN" calls in parallel.
2. Description of the Prior Art
In larger service control points which include several computing units for the parallel processing of IN calls, there are two major impediments which limit the service control point's achievable throughput (calls per time unit). The first impediment is the service control point's limited access to absolute counters. Absolute counters count events, i.e. calls, in order to effect certain functions such as call limitation or nth call. The second impediment is the service control point's limited access to RAM memories of computing units for storage of the routing data. Routing data is that which specifies the execution of a service at the service control point depending on the IN number.
For many IN services, one or several absolute counters are to be incremented per call. One computing unit is thereby respectively responsible for managing a particular absolute counter. If, however, a call that influences the state of this counter is processed on another computing unit, the order to increment the counter must first be sent to the computing unit responsible for the counter and then a corresponding response must be awaited. This results in a veritable communication bottleneck. It therefore follows that as the number of active computing units increases, the probability that an absolute counter is not present at the computing unit which is processing the call also increases. With the use of Ethernet as a communication medium, such increased communication can also lead to "treshing" (reduction of the achievable throughput at the bus due to an increased collision rate).
The storage of the routing data claims a very large number of storage units. For this reason, even with an expansion of the RAM memory on the order of 200 MB (or more), it is not possible to continually hold all of the routing trees, which contain the aforementioned routing data as well as the references to absolute counters, in a computing unit in the RAM memory.
If, for the reasons cited, the routing data required for a call is not located in the RAM memory, it must be loaded by a common memory for the computing units. Such process typically results in a memory bottleneck which, in turn, leads to time-consuming page faults (storage and retrieval processes of data and programs from the RAM memory). If the rate of page fault occurrence becomes too great, treshing may result which then leads to overly-slow call processing (resulting in high call error rates).